Q.No. 12:
Answer:
5.08 × 10²³ Glucose Molecules
Solution:
Data Given:
Mass of Glucose = 152 g
M.Mass of Glucose = 180.156 g.mol⁻¹
Step 1: Calculate Moles of Glucose as,
Moles = Mass ÷ M.Mass
Putting values,
Moles = 152 g ÷ 180.156 g.mol⁻¹
Moles = 0.8437 mol
Step 2: Calculate number of Glucose Molecules,
As 1 mole of any substance contains 6.022 × 10²³ particles (Avogadro's Number) then the relation for Moles and Number of glucose molecules can be written as,
Moles = Number of Glucose Molecules ÷ 6.022 × 10²³ Molecules.mol⁻¹
Solving for Number of Glucose Molecules,
Number of Glucose Molecules = Moles × 6.022 × 10²³ Molecules.mol⁻¹
Putting value of moles,
Number of Glucose Molecules = 0.8437 mol × 6.022 × 10²³ Atoms.mol⁻¹
Number of Glucose Molecules = 5.08 × 10²³ Glucose Molecules
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Q.No. 12: (A)
Answer:
3.04 × 10²⁴ Carbon Atoms
Solution:
The molecular formula of Glucose is C₆H₁₂O₆. This specifies that there are six carbon atoms in one molecule of Glucose.
Hence, when,
1 molecule of Glucose contain = 6 atoms of Carbon
Then,
5.08 × 10²³ Glucose Molecules will contain = X atoms of Carbon
Solving for X,
X = 5.08 × 10²³ molecules × 6 atoms / 1 molecule
X = 3.04 × 10²⁴ Carbon Atoms
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Q.No. 12: (B)
Answer:
1.22 × 10²⁵ Atoms in total
Solution:
The molecular formula of Glucose is C₆H₁₂O₆. This specifies that there are 6 carbon atoms, 12 hydrogen atoms and 6 oxygen atoms in one molecule of Glucose. So, there are 24 atoms in one molecule of glucose
Hence, when,
1 molecule of Glucose contain = 24 atoms
Then,
5.08 × 10²³ Glucose Molecules will contain = X atoms
Solving for X,
X = 5.08 × 10²³ molecules × 24 atoms / 1 molecule
X = 1.22 × 10²⁵ Atoms in total
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Q. No. 13
Answer:
1061.81 g of Aluminium
Solution:
Data Given:
Number of F.Units = 2.37 × 10²⁵
A.Mass of Aluminium = 26.98 g.mol⁻¹
Mass of Aluminium = ?
Step 1: Calculate Moles of Aluminium,
Moles = Number of F.Units ÷ 6.022 × 10²³ F.Units.mol⁻¹
Putting value,
Moles = 2.37 × 10²⁵ F.Units ÷ 6.022 × 10²³ F.Units.mol⁻¹
Moles = 39.35 mol
Step 2: Calculate Mass of Aluminium as:
Moles = Mass ÷ A.Mass
Solving for Mass,
Mass = Moles × A.Mass
Putting values,
Mass = 39.35 mol × 26.98 g.mol⁻¹
Mass = 1061.81 g of Aluminium
So, the form of scientific notation is 
